A modern solution used in particular for discharge type headlights is the combination of a distance light pattern and a dipped light pattern by means of a mechanism which is placed inside a projector lighting unit. As such, the mechanism provides a means for the movement of an optical element of the projector lighting unit, thereby providing both the distance light pattern and the dipped light pattern
Accordingly, the dipped light pattern and the distance light pattern may be generated by a single source having an uninterrupted discharge. A presently customary mechanism is known as a bifunctional (bi-xenon) element. However, other multifunctional mechanisms are already in the stage of experimentation, startup production, or series production.
Most of the conventional multifunctional mechanisms make use of a revolving diaphragm to change and control a light cropping. For example, the following patents describe the use of a diaphragm which can revolve about a transverse axis: DE 199 09 413 A1 of the Hella firm; U.S. Pat. Nos. 5,339,226 and 5,343,371 of the Koito firm; and EP 0 690 261 A1 of the Valeo firm.
Additionally, multifunctional mechanisms have to be reliable in operation under extreme conditions (temperature, vibration) within the headlight.
It would be desirable to develop a projector unit including a mechanism for changing a shape of a light cropping element and, thus, the spatial distribution of a light beam, wherein the projector unit provides reliable operation under temperature change and vibrations.